1883.] NATURAL SCIENCES OF PHILADELPHIA. 255 



thermometer indicated 42° ; but a quarter of a mile from the 

 immense body forming the mouth of the Muir glacier, the tem- 

 perature was 60^. These warm currents, however, vary with the 

 drafts tlirough the mountains. Within comparatively short dis- 

 tances, tlie temperature would vary from between 40° and 60° at 

 the time referred to. In the winter season the difference would 

 be the more remarkable, and hence a mountain or glacier torrent, 

 cutting out for itself a new channel, and making a deep rift in a 

 mountain, would originate a new current — warmer or colder, as the 

 ease might be — which must have an influence on the progress or 

 decrease of the glacier itself. The operations of these changes in 

 the atmospheric currents were ver}- evident in the vieinit}^ of the 

 Davidson glacier. Sometimes through chasms in the mountains 

 near, the whole mass of timber on either side would be quite dead 

 after having made a successful stand for from twenty-five to fifty 

 years, by the work of some severe cold current, which, hy some 

 local change, had found its wa3' along the course. Near by, on 

 land no better, quite as steep, and in no way more favoiable to the 

 growth of vegetation, the timber would be perfectly healthy, the 

 onl}' difference being in the freedom from the atmospheric current 

 that had destroyed the others. In short, the age of the trees on 

 the successive terraces left by the waters along the line of the 

 glacier's retreat, showed how much had been done within a com- 

 paratively recent period, and other attending facts showed that 

 local causes, induced by the glacier itself, may ripidly retard or 

 accelerate its development at various peiiods in its existence. 



In the retreat of the glaciers, in this part of Alaska, an alder, 

 Alnus viridis, was apparently the first arborescent plant to 

 establish itself. Large tracts of the drift would be wholly 

 covered by a dense, bushy growth. In time, however, many of 

 these would advance to the dimensions of large timber-trees, 

 surprising to those who might have only seen them as eight- or 

 ten-feet bushes in other parts of the United States In the woods 

 bordering on the Davidson glacier, the speaker saw Indians at 

 work making canoes (dug-outs) from the trunks of this alder. 



Favorable Injfuenee of Climate on Vegetation in Alaska. — In his 

 remarks on glaciers in Alaska, Mr. Thomas Meehan observed that 

 on the tops of what are known as " totem-poles " in some of the 

 Ind\an villages, trees of very large size would often be seen 

 growing. These poles are thick logs of hemlock or spruce, set 

 up before the doors of Indian lodges, carved all oyer with queer 

 characters representing living creatures of every description, and 

 which are supposed to be genealogies, or to tell of some famous 

 event in the family history'. They are not erected by Indians 

 now, and it i« difficult to get any connected accounts of what 

 they really tell. At the old village of Kaigan there are numbers 

 of poles erected, with no carving at all on them, among many 

 which are wholl^^ covered, and these all had one or more 



